The mosquito repellents that reliably work use an EPA-registered active ingredient: DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE) or PMD, or 2-undecanone. DEET at 15 to 30 percent protects for 6 to 12 hours, and picaridin is at least as effective. Higher concentration lasts longer, not stronger.
The simplest way to choose a mosquito repellent is one clear framework we call the Registered-First rule: start with a product built on an EPA-registered active ingredient, then match the concentration to how long you will be outside. EPA registration means the product was reviewed for both safety and effectiveness when used as directed, which is why it beats guessing among unproven sprays and plants. This matters because mosquitoes are, by disease transmission, the deadliest animals to humans, so the repellent you pick has real stakes.
Below, we cover the EPA-registered ingredients that work, how DEET and picaridin compare, and why the number on the bottle controls how long you are protected rather than how strongly. For the wider picture, see our overview of mosquitoes, and if you are treating a yard or home, how to get rid of mosquitoes.
Best Mosquito Repellents (EPA-Registered)
There is no single "best" spray, but there is a best category: repellents built on an EPA-registered active ingredient. Registration confirms the product was evaluated for safety and effectiveness. Five active ingredients carry that registration, and each is a legitimate choice.
DEET — the long-standing benchmark; broad, well-studied protection.
Picaridin — at least as effective as DEET, often preferred for feel.
IR3535 — an EPA-registered synthetic option.
Oil of lemon eucalyptus (OLE) / PMD — the para-menthane-diol form; the one plant-based option the CDC recommends.
2-undecanone — an EPA-registered active ingredient.
Among plant-based choices, OLE and its refined form PMD stand apart because it is the only botanical with a CDC recommendation. Pure essential oils such as citronella typically last only a short time, and plants marketed as repellents have weak real-world effect. If you want to weigh the botanical route, read natural mosquito repellent. According to the EPA, registered repellents are also safe for pregnant and breastfeeding women when used as directed.
DEET vs Picaridin
DEET and picaridin are the two most common choices, and the evidence puts them on roughly even footing. DEET at 15 to 30 percent gives about 6 to 12 hours of protection. Picaridin at 10 to 20 percent is at least as effective as DEET; in a field study, picaridin at 20 percent delivered 97.4 percent protection over 5 hours, equivalent to DEET at 20 percent. Both work — the choice comes down to preference.
DEET 15–30% = 6–12 h; picaridin 10–20% = 6–12 h and 20% gave 97.4% protection over 5 h. Sources: CDC, EPA, NIH/PMC4270489.
How Concentration Affects Protection Time
The most common myth is that a higher percentage repels mosquitoes more forcefully. It does not. A higher concentration extends how long the protection lasts, not how strongly it works. DEET at 15 to 30 percent lasts about 6 to 12 hours, while a very low concentration under about 10 percent lasts only around 2 hours.
Practically, that means you should match the number on the bottle to your plans: a short evening on the porch needs far less than a full day hiking. Reapply as the label directs once the protection window closes. For bite care and what a mosquito bite looks like, see mosquito bites.
Repellent Is Only Half the Job
Repellent protects your skin, but it does not reduce the mosquito population around you. To do that, remove the breeding source:
Eliminate standing water — saucers, buckets, clogged gutters, tires, and birdbaths — since larvae develop only in water.
Empty or refresh water-holding containers weekly to break the larval cycle.
Which mosquito repellent ingredients does the EPA register?
The EPA registers several active ingredients for skin-applied mosquito repellents: DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE) and its synthesized form PMD (para-menthane-diol), and 2-undecanone. EPA registration means the product has been reviewed for both safety and effectiveness when used as directed.
Is DEET or picaridin better for mosquitoes?
Both work well. DEET at 15 to 30 percent gives about 6 to 12 hours of protection, and picaridin at 10 to 20 percent is at least as effective as DEET. In one field study, picaridin at 20 percent provided 97.4 percent protection over 5 hours, equivalent to DEET at 20 percent. Choose the one you prefer to wear.
Does a higher concentration mean stronger protection?
No. A higher concentration lasts longer, it does not repel more strongly. DEET at 15 to 30 percent protects for about 6 to 12 hours, while very low concentrations under 10 percent last only about 2 hours. Pick the concentration that matches how long you will be outdoors.
Are there natural mosquito repellents that work?
Oil of lemon eucalyptus (OLE) and its refined form PMD is the only plant-based option with a CDC recommendation, and it is EPA registered. Pure essential oils such as citronella usually work only for a short time. For a fuller comparison, see natural mosquito repellent.
Are EPA-registered repellents safe during pregnancy?
According to the EPA, registered repellents are safe for pregnant and breastfeeding women when used as directed on the label. EPA registration reflects a review of both safety and effectiveness. Always follow the product instructions for application and reapplication.
How long does DEET protect against mosquitoes?
DEET at 15 to 30 percent provides roughly 6 to 12 hours of protection, according to CDC and NIH sources. Concentrations under about 10 percent protect for only around 2 hours. The higher percentages extend duration rather than increasing repelling strength.
Do mosquito repellent plants keep mosquitoes away?
Plants marketed as mosquito repellents, such as citronella, lavender, and catnip, have weak real-world effect and are no substitute for an EPA-registered repellent or removing standing water. Treat them as decorative, not as reliable protection.
Sources
U.S. EPA — Find the Repellent Right for You (EPA-registered active ingredients: DEET, picaridin, IR3535, OLE/PMD, 2-undecanone; registration = safety and effectiveness; safe for pregnant and breastfeeding women as directed).
CDC — Preventing Mosquito Bites (DEET 15–30% ≈ 6–12 hours; OLE is the only botanical with a CDC recommendation; pure essential oils are short-acting).